Backlight module is one of an essential device in a liquid crystal display (LCD) and configured to provide display light for a LCD panel. Today, backlight module is required to have a slimmer thickness in response to the trend of compact features for an LCD device. Thus, a conventional structure of a backlight module is disclosed as illustrated in FIG. 1.
As shown in FIG. 1, the conventional backlight module 100 includes a light guide plate 110, a reflective cavity 120 and a plurality of light emitting devices 130. The reflective cavity 120 has an opening 121 and an end surface 122; wherein the opening 121 and the end surface 122 are configured to be opposite to each other. The light guide plate 110 has a side surface 112, which is configured to be jointed to the opening 121 of the reflective cavity 120. The light emitting devices 130 are disposed on the end surface 122 of the reflective cavity 120. In order to response the compact feature of the light guide plate 110, the reflective cavity 120, with a wedge shape and functioned as a light coupling device, is configured to direct the light provided from the light sources 130 to the inside of the light guide plate 110.
However, the reflective cavity 120, due to having a hollow structure, has a relatively weak structural strength and accordingly is deformed easily. Moreover, because the reflective cavity 120 has a larger size and needs a complicated manufacture process, it is quietly difficult to realize the mass production of the reflective cavity 120. In addition, the reflective cavity 120, due to the structural limit, is difficult to be assembled to the light guide plate 110 and consequently may result in relatively poor assembly efficiency.